1. Field of the Invention
The present invention relates to a pixel structure, an array substrate and a method of fabricating the same, and more particularly, to a pixel structure having a conductive protection layer for protecting a metal layer, an array substrate and a method of fabricating the same.
2. Description of the Prior Art
The liquid crystal display (LCD) panel is characterized by light weight, low power consumption, and low radiation, and is widely applied in portable electronic products such as notebook computers, personal digital assistant (PDAs), and video camera. the LCD panel in the prior art is composed of an array substrate, a color filter substrate, and a liquid crystal layer, and rotation angles of liquid crystal molecules in the liquid crystal layer could be adjusted through controlling a voltage applied between a pixel electrode of the array substrate and a common electrode of the color filter substrate so as to display a required frame.
Generally, the array substrate in the prior art includes a plurality of data lines, a plurality of scan lines, a plurality of common lines, and a plurality of thin-film transistors (TFTs). The scan lines, the common lines and gates of the TFTs are constituted by a first metal layer, and the data lines and sources and drains are constituted by a second metal layer. In addition, each TFT has a semiconductor layer serving as its channel. However, the first metal layer and the second metal layer are generally made of aluminum, so that when aluminum is in contact with silicon of the semiconductor layer, aluminum is easily diffused into the semiconductor layer, and the operation of each TFT is affected by the diffusion. For this reason, in order to avoid the source and the drain composed of aluminum being diffused into silicon, a molybdenum (Mo) metal layer is disposed between the semiconductor layer and the second metal layer in the array substrate of the prior art. Besides, another Mo metal layer is disposed on the first metal layer, and another Mo metal layer is disposed on the second metal layer in the array substrate of the prior art, so that the first metal layer and the second metal layer composed of aluminum could be avoided being oxidized or corroded.
However, in the method of fabricating the array substrate in the prior art, the first metal layer and the Mo metal layer disposed thereon are formed in the same etching process, and the second metal layer, the Mo metal layer disposed thereon and the Mo metal layer disposed there under are formed in the same etching process. In addition, the etching rate of aluminum and the etching rate of the Mo are different, so that the formed first metal layer, the formed second metal layer and the formed Mo metal layer have overhangs, and a problem of the insulating layer and the passivation layer formed in the following step having bad coverage on the overhangs is generated.